Evaluate the following ratios for the energy of the electron in a particular orbit:
[Kinetic $:$ Potential] and [Total $:$ Kinetic]

The ionization energy of an electron in an excited state of a hydrogen atom is $+0.85 \, eV$. What will be the energy of the emitted photon in $eV$ when it returns to the ground state?

The energy of the second Bohr orbit of the hydrogen atom is $-3.4 \ eV$. The energy of the fourth Bohr orbit of the $He^{+}$ ion will be: (in $eV$)

If the ratio of energies of an electron in the excited states of $H$ and $Li^{2+}$ is $1: 9$,the radius ratio of the electron in the same excited states of $H$ and $Li^{2+}$ is

Given below are two statements:
Statement $I$: Bohr's theory accounts for the stability and line spectrum of $Li^{+}$ ion.
Statement $II$: Bohr's theory was unable to explain the splitting of spectral lines in the presence of a magnetic field.
In the light of the above statements,choose the most appropriate answer from the options given below:

In astronomical observations,signals observed from the distant stars are generally weak. If the photon detector receives a total of $3.15 \times 10^{-18} \, J$ from the radiations of $600 \, nm$,calculate the number of photons received by the detector.